...when instantiating implicitly defined special member functions of
SVX_DLLPUBLIC SdrCustomShapeGeometryItem, due to aPropSeq member

Change-Id: I7fc0ba1db3aa67bdd5c4d8878504a31f32b42ffd
Reviewed-on: https://gerrit.libreoffice.org/73405
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>